Dyeing process



United States Patent 3,132,918 DYEING PRWCESS Alton Lee Corpening, Danvilie, Van, assignor to Dan River Mills, Incorporated, Danviiie, Van, a corporation of Virginia No Drawing. Filed Feb. 26, 1962, Ser. No. 174,375 4 filiaims. (til. 8-54.2)

This invention is directed to a process for dyeing Alcian Blue on textiles, especially cellulosic textile yarns and, more particularly, relates to the dyeing of such yarns on packages or beams in dyeing machines.

Some conventional dyeing machines comprise a kier into which a package or beam of wound yarn having a hollow core is inserted, an expansion tank, a dyebath pump and a reversing valve and an overflow pipe leading from the top of said kier to the expansion tank. Two pipes connect the bottom of the expansion tank to the kier. One pipe communicates with the hollow core of the beam or package and the other pipe communicates with the outside area of the beam or package. The reversing valve is interposed in both pipes to control the direction of flow therein. The pump is interposed in one of the pipes for the purpose of circulating the dyebath in the system. Other arrangements of the same general system are employed. For example, two pumps connected through a T to the expansion valve can be employed in place of the combination of a pump and reversing valve. In general, any arrangement of pumps, valves and piping which will circulate dyebath from the expansion tank to the hollow core of the beam or package within the kier and return dyebath from the external areas of said beam or package to the expansion tank and alternatively circulate dyebath from the expansion tank to the external areas of the beam or package within the kier and return the dyebath from the hollow core of the beam or package to the expansion tank is employed.

Machine dyeing methods have heretofore involved the use of a volatile acid, e.g., acetic acid, to promote solution of the dye in preparing the dyebath and while dyeing was being performed. In addition, a cation active reagent was employed to retard the dyeing and final exhaustion of the dye onto the yarn was accomplished by raising the temperature which evaporated the volatile acid to raise the pH of the dyebath.

The prior art machine dyeing methods required that the yarn be previously bleached and did not permit the dyeing of light shades. In addition, complete exhaustion of the dyebath was not possible by prior art methods and longer dyeing times and higher dyeing temperatures were necessary. While the prior methods usually provided dyed yarns which were suitable for use, uneven dyeings were constantly a problem. In addition, close temperature and pH controls were necessary in prior methods in order to obtain commercially satisfactory dyeings.

It is therefore a principal object of this invention to dddzfil Patented May 12, 1964 light shades heretofore unobtainable by machine dyeing methods.

The novel machine dyeing process of thisinvention comprises the steps of treating cellulosic textile yarn with an aqueous acid solution, dyeing said yarn with a dyebath at a low pH and slowly feeding a bulfer into said dyebath during the final stages of dyeing, said butter being capable of raising the dyebath pH to a level up to about 4. The novel process is especially adaptable to dyes comprising the reaction products of thiourea with chloromethylate copper phthalocyanine and which are represented by the provide a novel machine dyeing method which is capable of providing uniform dyeing of all shades including light shades without the necessity of close temperature controls.

It is another object of this invention to provide a machine dyeing process to provide evenly dyed yarns.

It is an additional object of this invention to provide a machine dyeing process which can be used, if desired, to dye unbleached yarns.

A further object is the provision of a machine dyeing process wherein the dyeing temperature and dyeing time are considerably reduced and wherein more complete exhaustion of the dyebath is obtained.

A further object is the provision of a novel machine dyeing process which will permit the dyeing of yarns to formula wherein X is a group of the formula R being an alkyl or aryl group. These dyes are described in British Patents No. 586,340 and No. 587,636. Commercially they are known as the Alcian Blue dyes, e.g., Alcian Blue 7GX or Alcian Blue 8GX made by Imperial Chemical Industries, Ltd., and sold by Arnold, Hoffman & Co.

The acids which may be used in the novel dyeing process are any of the usual acids employed heretofore. Illustrations of such acids include onganic and mineral acids such as acetic, formic, hydrochloric, sulfuric acids and the like. Typical butters that can be employed are those which would provide a pH up to about 4 such as, for example, sodium formate, sodium acetate and the like. The amount of acid employed is suflicient to adjust the pH of the acid treating solution to a value of 2 or below and the amount of bufier employed is suflicient to raise the dyebath to a pH of 3.5 to 4.5. When an amount of butter is employed to raise the dyebath pH to about 3.5, lighter shades are obtained and heavier shades are obtained when the buffer raises the dye bath pH to a value of 4.5. In

' this regard, sodium formate is a most advantageous buifer to employ in that the pH of the dyebath is more easily controllable within the above specified range and dye precipitation which dulls the dyeing and makes it susceptible to bleeding during aftertreatment as caused by too high a dyebath pH is avoided.

In carrying out the novel dyeing process, a dyeing machine is loaded with a package or beam of yarn to be dyed and an acid solution at a pH of about 2 or less (but not so low as to deteriorate the yarn) is run through the machine. The dye is pasted with a suitable solubilizer such as ethylene glycol ethyl ether with or without an acid such as acetic acid and diluted with water. The resulting dye solution is fed into the dye machine containing the above-mentioned aqueous acid solution and it is preferred to add half of said dye solution while the machine is running in,-to-out and the remaining half while the machine is running out-to-in. After all of the dye solution has been added, the machine is run for a sufiicient time alternatively out-to-in and in-to-out (or conversely in-to-out and outto-in) for a sufficient time for a practical equilibrium to be established between the dye in the dyebath and the dye in the yarn at the pH of the dyebath. An aqueous solution of the butter is then slowly fed into the dyebath to slowly raise the pH to a value within the range of 3.5 to 4.5 (preferably about 4.0) and exhaust the dyebath. The yarn thus dyed is then aftertreated in the usual manner, for example, with an insolubilizer, e.g., sodium carbonate, washing, rinsing and the like, after which the yarn is re moved from the machine.

The novel process as described above is capable of providing uniform dyeing of all shades including light shades which heretofore could not be accomplished by previous methods. In addition, the dyebath is more completely exhausted and the time of dyeing and temperature of dyeing are considerably lowered. In addition, if desired, unbleached yarn can be dyed by this method in contradis tinction to prior methods which required that the yarn be leached before dyeing.

The following example is presented.

Example A 750 pound load of 30/1 cotton yarn was dyed on a package machine made by Gaston County Dyeing Machine Company. The procedure was as -iollows:

A package of the yarn was Wet out and bleached as usual. The machine was filled with water heated to 140 F. and primed with pounds of concentrated sulfuric acid, 7 pounds of acetic acid, 84%, and pounds of formic acid and was run for about 2 minutes to acidify the yarn.

Six pounds of Alcian Blue 86X 300%, Color Index No. 74,240, was pasted with 6 pounds of ethylene glycol ether and 3 pounds of acetic acid, 84%, stirred and brought up to 20 gallon volume with water at F.

This dye solution was fed into machine by gravity; onehalf of dye being fed while pumping from the outside of the package to the inside and one-half being fed while pumping from the inside of the package to the outside. The machine was, then operated to pump seven minutes out-to-in and 5 minutes in-to-out.

Thirty-five pounds of sodium formate was dissolved in 20 gallons of water and the resulting solution was allowed to slowly flow by gravity into the machine over a period of 40 minutes. This brought the pH of the dyebath from 2 up to 4.

The bath was then heated to 195 F over a period of 10 minutes. The dyebath was dropped and the yarn was rinsed with cold water.

Twenty-five pounds of sodium carbonate was then added and the bath was heated to F. Four pounds machine run for 20 minutes. with cold water and removed.

The yarn was then washed While this invention has been described in terms of dyeing yarns because of its particular values in such dyeings, it will be obvious to those skilled in the art that the improvements disclosed and claimed are also applicable to dyeing of cellulosics in the form of fibrous raw stock and woven fabric.

What is claimed is:

l. A process for dyeing cellulo sic textile yarn wound in packages and beams in a dyeing machine comprising treating said yarn with an aqueous acid solution, dyeing said yarn with an aqueous solution of Alcian Blue, Color Index No. 74,240, at a pH of not more than 2, and thereafter gradually adding an aqueous solution of sodium formate to said dyebath to thereby gradually increase the pH of said dyebath to a value in the range of 3.5 to 4.5.

2. In a process of dyeing cellulosic textile yarn wound in packages and beams in a dyeing machine wherein the yarn is initially acidified with an aqueous acid solution and thereafter dyed with an aqueous dyebath comprising Alcian Blue, Color Index No. 74,240, the improvement comprising conducting said pretreatment and dyeing at a pH of not more than 2 and gradually adding an aqueous solution of a compound from the class consisting of sodium formate and sodium acetate to gradually increase the pH of said dyebath to a value in the range of 3.5

3. A process for dyeing cellulosic textiles wound in packages and beams comprising treating said textiles with an aqueous acid solution, dyeing said textiles withan aqueous solution of Alcin Blue, Color Index No. 74,240, at a pH of not more than 2, and thereafter gradually adding an aqueous solution of sodium formate to said dyebath to thereby graduallyincrease the pH of said dyebath to a value in the range of 3.5 to 4.5.

4. In a process of dyeing cellulosic tertiles wound in packages and beams wherein the textiles are initially acidiiied with an aqueous acid solution and thereafter dyed with an aqueous dyebath comprising Alcian Blue, Color Index No. 74,240, the improvement comprising conducting said pretreatment and dyeing at a pH of not more than 2 and gradually adding an aqueous. solution of a compound from the class consisting of sodium formate and sodium acetate to gradually increase the pH of said dyebath to a value in the range of 3.5 to 4.5.

References Cited in the file of this patent FOREIGN PATENTS 633,160 Great Britain Dec. 12, 1949 633,602 Great Britain Dec. 19, 1949 

1. A PROCESS FOR DYEING CELLUOSIC TEXTILE YARN WOUND IN PACKAGES AND BEAMS IN A DYEING MACHINE COMPRISING TREATING SAID YARN WITH AN AQUEOUS ACID SOLUTION, DYEING SAID YARN WITH AN AQUEOUS SOLUTION OF ALCIAN BLUE, COLOR INDEX NO. 74240, AT A PH OF NOT MORE THAN 2, AND THEREAFTER GRADUALLY ADDING AN AQUEOUS SOLUTION OF SODIUM FORMATE TO SAID DYEBATH TO THEREBY GRADUALLY INCREASE THE PH OF SAID DYEBATH TO A VALUE IN THE RANGE OF 3.5 TO 4.5. 